292 research outputs found
Prokaryotic variables from a indoor-mesocosm experiment measured during the winter in the Northern Bothnian Sea
No full textThe primary data was collected during the indoor-mesocosm experiment conducted in March 2020 at Umea Marine Science Centre, Umea University, Sweden situated in the Northern Bothnian Sea (63° 34ˈN, 19° 50ˈE). A full factorial experiment was set with temperature and the addition of nutrients as treatment factors with a natural pelagic food web containing all trophic levels except fish. A total of four experimental treatments were set up with three replicates each: C, control (1°C, no additions); N (1°C,+ nutrients); T (10°C, no additions) and TN (10°C, + nutrients). For each treatment, eight different samplings were done in triplicates. The variables in the data include the prokaryotic abundance (PA), growth (PG), respiration (PR), specific prokaryotic respiration (ρ), specific growth rates (µ), growth efficiency (PGE), dissolved organic carbon (DOC), total dissolved phosphorus (TDP) and total dissolved nitrogen (TDN)
Adaptations of Microorganisms to Low Nutrient Environments: Managing Life in the Oligotrophic Ocean
No full textLow-nutrient environments are abundant and widespread across Earth, in terrestrial, freshwater, and marine environments, and from a microbial perspective may thus be regarded as the norm rather than an exception. Consequently, an extraordinary variety of adaptations have evolved among microorganisms to survive, and even reproduce, when nutrients are scarce. Here we first present an overview of the physicochemical and biological conditions that determine the transition from nutrient rich coastal environments to the low-nutrient (oligotrophic) situation that dominates the open ocean. We thereafter present genetic, physiological and metabolic adaptations important for marine bacteria to compete successfully in open ocean environments, noting that SAR11 group bacteria (Alphaproteobacteria) and cyanobacterial Prochlorococcus are among the most abundant organisms in the open ocean. Distinct adaptations are necessary for adjusting to limited availability of dissolved organic carbon, the macronutrients nitrogen and phosphorous, or micronutrients like iron (and other trace metals) or vitamins. Moreover, a multitude of distinct bacterial groups use photosystems based on rhodopsins or bacteriochlorophyll to harvest energy from sunlight. The spatial and temporal distribution of microorganisms, as influenced by nutrient availability, can be expected to have major importance in determining biogeochemical cycles of elements necessary for life and the flux of energy through ecosystems. © 2019 Elsevier Inc. All rights reserved.</p
Genomics of the proteorhodopsin-containing marine flavobacterium Dokdonia sp. MED134
No full textGonzalez JM, Pinhassi J, Fernández-Gómez B, et al. Genomics of the proteorhodopsin-containing marine flavobacterium Dokdonia sp. MED134. Applied and Environmental Microbiology. 2011;77(24):8676-8686
Differential growth response of colony-forming alpha- and delta-proteobacteria in dilution culture and nutrient addition experiments from lake Kinneret (Israel), the Eastern Mediterranean Sea, the Gulf of Eilat
No full textBacterioplankton in the light of seasonality and environmental drivers [Elektronisk resurs]
No full textBacterioplankton are keystone organisms in marine ecosystems. They are important for element cycles, by transforming dissolved organic carbon and other nutrients. Bacterioplankton community composition and productivity rates change in surface waters over spatial and temporal scales. Yet, many underlying biological processes determining when, why and how bacterioplankton react to changes in environmental conditions are poorly understood. Here, I used experiments with model bacteria and natural assemblages as well as field studies to determine molecular, physiological and ecological responses allowing marine bacteria to adapt to their environment.Experiments with the flavobacterium Dokdonia sp. MED134 aimed to determine how the metabolism of bacteria is influenced by light and different organic matter. Under light exposure, Dokdonia sp. MED134 expressed proteorhodopsin and adjusted its metabolism to use resources more efficiently when growing with lower-quality organic matter. Similar expression patterns were found in oceanic datasets, implying a global importance of photoheterotrophic metabolisms for the ecology of bacterioplankton.Further, I investigated how the composition and physiology of bacterial assemblages are affected by elevated CO2 concentrations and inorganic nutrients. In a large-scale experiment, bacterioplankton could keep productivity and community structure unaltered by adapting the gene expression under CO2 stress. To maintain pH homeostasis, bacteria induced higher expression of genes related to respiration, membrane transport and light acquisition under low-nutrient conditions. Under high-nutrient conditions with phytoplankton blooms, such regulatory mechanisms were not necessary. These findings indicate that open ocean systems are more vulnerable to ocean acidification than coastal waters.Lastly, I used field studies to resolve how bacterioplankton is influenced by environmental changes, and how this leads to seasonal succession of marine bacteria. Using high frequency sampling over three years, we uncovered notable variability both between and within years in several biological features that rapidly changed over short time scales. These included potential phytoplankton-bacteria linkages, substrate uptake rates, and shifts in bacterial community structure. Thus, high resolution time series can provide important insights into the mechanisms controlling microbial communities.Overall, this thesis highlights the advantages of combining molecular and traditional oceanographic methodological approaches to study ecosystems at high resolution for improving our understanding of the physiology and ecology of microbial communities and, ultimately, how they influence biogeochemical processes.</p
Marine bacterioplankton seasonal succession dynamics
No full textBacterioplankton (bacteria and archaea) are indispensable regulators of global element cycles owing to their unique ability to decompose and remineralize dissolved organic matter. These microorganisms in surface waters worldwide exhibit pronounced seasonal succession patterns, governed by physicochemical factors (e.g., light, climate, and nutrient loading) that are determined by latitude and distance to shore. Moreover, we emphasize that the effects of large-scale factors are modulated regionally, and over shorter timespans (days to weeks), by biological interactions including molecule exchanges, viral lysis, and grazing. Thus the interplay and scaling between factors ultimately determine the success of particular bacterial populations. Spatiotemporal surveys of bacterioplankton community composition provide the necessary frame for interpreting how the distinct metabolisms encoded in the genomes of different bacteria regulate biogeochemical cycles.</p
Sensitivity of Bacterioplankton to Environmental Disturbance : A Review of Baltic Sea Field Studies and Experiments
No full textBacterioplankton communities regulate energy and matter fluxes fundamental to all aquatic life. The Baltic Sea offers an outstanding ecosystem for interpreting causes and consequences of bacterioplankton community composition shifts resulting from environmental disturbance. Yet, a systematic synthesis of the composition of Baltic Sea bacterioplankton and their responses to natural or human-induced environmental perturbations is lacking. We review current research on Baltic Sea bacterioplankton dynamics in situ (48 articles) and in laboratory experiments (38 articles) carried out at a variety of spatiotemporal scales. In situ studies indicate that the salinity gradient sets the boundaries for bacterioplankton composition, whereas, regional environmental conditions at a within-basin scale, including the level of hypoxia and phytoplankton succession stages, may significantly tune the composition of bacterial communities. Also the experiments show that Baltic Sea bacteria are highly responsive to environmental conditions, with general influences of e.g. salinity, temperature and nutrients. Importantly, nine out of ten experiments that measured both bacterial community composition and some metabolic activities showed empirical support for the sensitivity scenario of bacteria - i.e., that environmental disturbance caused concomitant change in both community composition and community functioning. The lack of studies empirically testing the resilience scenario, i.e., experimental studies that incorporate the long-term temporal dimension, precludes conclusions about the potential prevalence of resilience of Baltic Sea bacterioplankton. We also outline outstanding questions emphasizing promising applications in incorporating bacterioplankton community dynamics into biogeochemical and food-web models and the lack of knowledge for deep-sea assemblages, particularly bacterioplankton structure-function relationships. This review emphasizes that bacterioplankton communities rapidly respond to natural and predicted human-induced environmental disturbance by altering their composition and metabolic activity. Unless bacterioplankton are resilient, such changes could have severe consequences for the regulation of microbial ecosystem services
Various colony morphologies and coloration of different proteorhodopsin-containing bacteria used to study proteorhodopsin phototrophy.
No full text<p>From top to bottom, the flavobacterium <i>Polaribacter dokdonensis</i> strain MED152 used to show proteorhodopsin light stimulated growth <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1000359#pbio.1000359-GmezConsarnau1" target="_blank">[13]</a>; the flavobacterium <i>Dokdonia donghaensis</i> strain MED134 used to show proteorhodopsin light stimulated CO<sub>2</sub>-fixation <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1000359#pbio.1000359-Gonzlez1" target="_blank">[23]</a>; and <i>Vibrio</i> strain AND4 used to show proteorhodopsin phototrophy <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1000359#pbio.1000359-GmezConsarnau2" target="_blank">[16]</a>; note the lack of detectable pigments in <i>Vibrio</i> strain AND4. However, when these vibrio cells are pelleted, they do show a pale reddish color, which is the result of proteorhodopsin pigments presence in their membranes. Photos are courtesy of Jarone Pinhassi.</p
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